CPC H01M 4/525 (2013.01) [C01G 53/50 (2013.01); H01B 1/08 (2013.01); H01M 4/131 (2013.01); H01M 4/133 (2013.01); H01M 4/134 (2013.01); H01M 4/139 (2013.01); H01M 4/366 (2013.01); H01M 4/505 (2013.01); H01M 6/164 (2013.01); H01M 10/0525 (2013.01); C01P 2002/74 (2013.01); H01M 2004/028 (2013.01)] | 26 Claims |
1. A secondary battery comprising:
a positive electrode active material comprising lithium, cobalt, and oxygen,
wherein the positive electrode active material has a property that an X-ray diffraction pattern of the positive electrode active material has at least a first peak at 2θ of 19.30±0.20° and a second peak at 2θ of 45.55±0.10°, as analyzed by powder X-ray diffraction with a CuKα1 line in a charged state when charged with a lithium metal counter electrode at 25° C. and at 4.6 V, and
wherein the positive electrode active material further comprises magnesium, fluorine, and titanium,
wherein a discharge capacity retention rate of a coin cell comprising the positive electrode active material is higher than or equal to 74% and lower than or equal to 94% at the 50th cycle of a cycle test at 25° C., the coin cell comprising a lithium metal counter electrode, and
wherein, for each cycle of the cycle test:
a CCCV charge is performed at a current value of 0.5 C and a battery voltage of 4.6V, with a termination current of 0.01 C,
a CC discharge is performed at a current value of 0.5 C until the battery voltage reaches 2.5V, and
1 C is set to 137 mA/g.
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